To start off we were received with an upgrade to a room with a view and a welcoming platter of fruit and sangria. The staff in general were extremely pleasant, helpful and just charming. The pros for the Nidimos Hotel include: free underground parking (this in a town where parking is a pain--narrow streets, parking on the side of the road, etc); the breakfast buffet is really good, lots of food and variety; the rooms are spacious; location! the hotel is walking distance from the Delphi archaeological museum and site (or you can drive up and park there easily), there are also plenty of shops nearby (including a bakery and mini market).
The only con I would mention because I know it might bother other travelers is that the hotel is old. There's nothing wrong with it, everything works and is in perfect condition, but you can tell it's an old building when you enter the rooms.
I would absolutely return to this hotel!